K20P81M72SF1 Datasheet, PDF (47/74 Pages) Freescale Semiconductor, Inc – K20 Sub-Family

Peripheral operating requirements and behaviors
Table 28. 16-bit ADC with PGA characteristics (continued)
Symbol
E_IL
Description
Input leakage
error
Conditions
All modes
V_PP,DIFF
Maximum
differential input
signal swing
SNR
Signal-to-noise
ratio
THD
Total harmonic
distortion
• Gain=1
• Gain=64
• Gain=1
• Gain=64
SFDR
Spurious free
dynamic range
• Gain=1
• Gain=64
ENOB
Effective number
of bits
• Gain=1, Average=4
• Gain=64, Average=4
• Gain=1, Average=32
• Gain=2, Average=32
• Gain=4, Average=32
• Gain=8, Average=32
• Gain=16, Average=32
• Gain=32, Average=32
• Gain=64, Average=32
Min.
Typ.¹
I_In × R_AS
Max.
Unit
Notes
mV
I_In = leakage
current
(refer to the
MCU's voltage
and current
operating
ratings)
V
6
where V_X = V_REFPGA × 0.583
80
90
—
52
66
—
85
100
—
49
95
—
85
105
—
53
88
—
11.6
13.4
—
7.2
9.6
—
12.8
14.5
—
11.0
14.3
—
7.9
13.8
—
7.3
13.1
—
6.8
12.5
—
6.8
11.5
—
7.5
10.6
—
dB
16-bit
dB
differential
mode,
Average=32
dB
16-bit
dB
differential
mode,
Average=32,
f_in=100Hz
dB
16-bit
dB
differential
mode,
Average=32,
f_in=100Hz
bits
16-bit
bits
differential
mode,f_in=100H
bits
z
bits
bits
bits
bits
bits
bits
SINAD
Signal-to-noise
plus distortion
ratio
See ENOB
6.02 × ENOB + 1.76
dB
1. Typical values assume V_DDA =3.0V, Temp=25°C, f_ADCK=6MHz unless otherwise stated.
2. This current is a PGA module adder, in addition to ADC conversion currents.
3. Between IN+ and IN-. The PGA draws a DC current from the input terminals. The magnitude of the DC current is a strong
function of input common mode voltage (V_CM) and the PGA gain.
4. _{Gain = 2}^PGAG
5. After changing the PGA gain setting, a minimum of 2 ADC+PGA conversions should be ignored.
6. Limit the input signal swing so that the PGA does not saturate during operation. Input signal swing is dependent on the
PGA reference voltage and gain setting.
K20 Sub-Family Data Sheet, Rev. 2, 4/2012.
Freescale Semiconductor, Inc.
47